The present invention relates to the installation of prefabricated polyphase ac windings into the grooves of an elongated inductor structure of a linear motor.
The method and equipment of the type to which the invention pertains applies, for example, to those types of linear motors which include an inductor arranged along a track part having grooves open in down direction, and being fastened to the bottom of a cover plate of an elongated carrier having approximately the T-shaped profile. An arrangement of this type is, for example, disclosed in U.S. Pat. No. 4,310,966 including this feature and many of the following aspects of prior art construction and method, but differing from the invention as will be explained below. The prefabricated winding is a coherent ladder-like flexible cable assembly which, as a whole, is wound on a drum and hauled to the installation site. If the stator elements are not attached (as per this patent), then the inductor must be preassembled and fastened to the carrier and the cable assembly is step-by-step pressed by people into the grooves of the inductor under utilization of a support structure which is movable in some fashion along the inductor and arranged generally underneath thereof. Having, so to speak, the "rung" or "rungs" of the ladder forced into the grooves, additional steps are taken to maintain these rungs therein.
Generally speaking linear motors are known as an electric drive or better drive principle and they have been constructed in various ways. For example, they are known to operate as dc motors as ac synchronous motors, or as ac asynchronous motors. In the case of a linear motor, the stator as well as the "rotor" are not arranged in an annular or circular fashion, but along a line. Even though strictly speaking such a line can by and in itself be closed as far as the stator part is concerned, the operational principle is basically designed to have an indefinite beginning and indefinite end of such a stator. The movable element is not in the least geometrically matched to the overall contour of the stator and vice versa. Electrical energy is converted into mechanical energy to become immediately and directly usable as a translatory movement. In other words, a conversion from rotational movement into translatory movement is not necessary. The linear motor may generally be provided with an energization or exciter winding or coil arrangement being disposed in grooves of a stator, and one can readily provide a three phase configuration. This of course is shown in the above-mentioned patent. Further, to the state of the art in this regard, reference is made to U.S. Pat. Nos. 4,246,694 and 4,314,168.
The stator part generally in such a linear motor is constructed, for example, as a rail or bar made of electrically conductive material such as copper or aluminum. In this case then the motor is assumed to run on the asynchronous principle. Alternatively the runner may be constructed from permanent magnetic material, in which case a synchronous operational principle is employed. For purpose of completion, it should be mentioned that linear motors are known in which the winding is also or exclusively included in the movable element.
Linear motors of the type to which the invention pertains, and which have been referred to generally above, are, for example, used as transport vehicle, for example, as so-called people mover or in the field of conveying freight and other transport tasks. Also, production lines have been constructed with movable belts driven by such linear motor. Baggage transport and handling facilities are likewise known to be equipped with linear motors. Other fields are, for example, mining, crane dragging and carriages in machine tools, as well as structure for operating slides, gates, or the like. Depending upon the particular field of employment, the motor, i.e., the stator part, has to have a certain length. The windings are, as stated, placed in some fashion into the grooved of the stator, and it is obvious that the longer the stator is, the more extensive and expensive will be the work to place the windings into the stator assembly. Obviously this kind of work has often required highly skilled workers.
If a linear motor is constructed with a long stator carrying the energization winding, and if such a drive is to be used for transport in general, then the stator of course is to be arranged along a particular transport path to establish, so to speak, the track of conveyance and transport. In this case then the active part of the stator, i.e., the inductor, is assembled first, usually being comprised of many separated assemblies of sheet and plate stock, and they are fastened to a suitable carrier facility. That carrier may well be designated as a vehicle rail on which the transport vehicle runs. As stated above, the windings are subsequently placed into the grooves of the stator part, and as described in various ways in some of the above-identified patents. This winding therefore has to be placed from below into the grooves, even if no particular auxiliary equipment is employed. Moreover, the windings have to be subsequently fastened. All this is quite extensive, whereby it has to be observed that the work is to be done overhead, i.e., usually above the normal activity level of people which is particularly tiring.
German printed patent application 2,827,150 discloses a method in which now the entire prefabricated winding is first placed on a plurality of supports which are arranged under the inductor or stator part. This thus prepositioned winding is then step-by-step placed into the grooves of the inductor. However, this method is still quite expensive in spite of the great help established through the prefabrication of the conductor assembly because still one needs manual labor for forcing the "rungs" into the grooves.